1. Field of the Invention
This invention relates to a drive interface for connecting between a drive device for performing reading or writing of information and a controller for controlling the drive device.
2. Description of Related Art
There have been provided various kinds of information processing apparatus provided with disk drive devices for performing reading or writing of data for hard disks and the like and controllers for controlling said drive devices.
In such apparatuses, an interface for connecting the drive device and the controller also has developed from ST-506 to SMD (Storage Module Drive) and ESDI (Enhanced Small Device Interface) in accordance with the tendency toward large capacity hard disks and the like.
FIGS. 10 and 11 are model drawings showing signal lines in the above-described ESDI.
In the ESDI, the following six kinds of signal lines are necessary for the disk drive and write/record data:
(1) Write Gate (the 6th pin in FIG. 11); PA1 (2) Read Gate (the 32nd pin in FIG. 11); PA1 (3) Write Clock (the 7th and 8th pins in FIG. 10); PA1 (4) Read Clock (the 10th and 11th pins in FIG. 10); PA1 (5) Write Data (the 13th and 14th pins in FIG. 10); and PA1 (6) Read Data (the 17th and 18th pins in FIG. 10). PA1 (1) Transfer Ack (the 10th pin in FIG. 11); PA1 (2) Transfer Req (the 24th pin in FIG. 11); PA1 (3) Command Data (the 34th pin in FIG. 11); and PA1 (4) Config/Status Data (the 8th pin in FIG. 11).
Furthermore, for communication of command/status between the disk drive device and the controller, the following four kinds of signal lines are necessary:
Accordingly, in the drive interface of the above-described ESDI, six kinds of signal lines are necessary for data communication between the disk drive device and the controller for the communication of write/read data, and four kinds of signal lines are necessary for the communication of command/status data, That is, ten kinds of signal lines are necessary in total. Consequently, the width of a cable for the drive interface becomes large. Hence, there are problems in that it is troublesome to handle the resulting cables, and the cost of the cables increases.
An analysis of the flow of data on the drive interface indicates that always only one kind of data is transmitted at any given time in the case of transmission and reception of data (write data, read data, command data and status data) between the controller and the disk drive device.
Accordingly, there exist plural unused signal lines, and signal lines are not effectively utilized.
Furthermore, the number of devices for data communication is also large.